Your butter should be at room temperature before you add it to your mashed potatoes.
A mix-in can spice up any mashed potato dish. Try caramelized onions, prepared horseradish, bacon bits, roasted garlic, or chipotle peppers.
For calorie and fat control, use fat-free chicken or vegetable broth in place of milk and butter when mixing potatoes.
Use leftover mashed potatoes as thickeners for soups, stews, and sauces. Or, you could make potato pancakes. Just substitute mashed potatoes for flour in your favorite pancake recipe.